Transfer system for cryogenic liquids



Sept. 22, 1970 A. HAREL v TRANSFER SYSTEM FOR CRYOGENIC LIQUIDS Filed Oct. 16, 1968 2 Sheets-Sheet 1 NVENTOR.

Sept. 22, 1970 A. HAREL "3,529,429

TRANSFER SYSTEM FOR CRYOGENIC LIQUIDS Filed Oct. 16, 1968 2 Sheets-Sheet 2 United States Patent O 3,529,429 TRANSFER SYSTEM FOR CRYOGENIC LIQUIDS Abraham Hare], Trenton, N.J., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Air Force Filed Oct. 16, 1968, Ser. No. 768,147 Int. Cl. Btlld 5/00 U.S. Cl. 62-555 4 Claims ABSTRACT OF THE DISCLOSURE A cooling system has the cooling liquid, for example liquid-nitrogen or liquid helium, from a pressure tank, supplied through a T connector to the center of a helical coil. The axis of the coil is substantially vertical so that the gas formed in the coil will rise to the top turns of the coil. The output is taken otf a second T connector at the top of the coil. A second coil providing a high impedance path is connected between the bottom of the cooling coil and the top of the cooling coil through the second T connector.

BACKGROUND OF THE INVENTION Coils containing liquid nitrogen or other cryogenic liquids are widely used in vacuum systems such as in forming baffies for oil diffusion pumps and cryogenic pumps or meissner traps. In these systems the cooling liquid must be transferred from a pressurized tank into the coils. A common problem with these systems is that the liquid coolant warms up in the coils and in the pipes which lead from the tank to the coil. During the refilling process a burst of warm gas from the pipes leading to the coil will cause the liquid coolant remaining in the coil to be ejected thus permitting the entire coil to warm up and cause a pressure rise in the vacuum system. This also causes a waste of liquid coolant.

SUMMARY OF THE INVENTION According to this invention the liquid coolant is fed at the center of a helical cooling coil through an input T connector. The axis of the cooling coil is vertical to permit the gas to rise to the top turns by gravity. The output at the top of the coil also has a T connector. A high impedance passage is provided between the output T connector at the top of the cooling coil and the bottom of the cooling coil.

BRIEF DESCRIPTION OF THE DRAWINNG FIG. 1 is a top plan view of the liquid-nitrogen transfer system of the invention; and

FIG. 2 is a front end view of the device of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to FIG. 1 of the drawing which shows a cooling coil for cooling a vacuum system apparatus, not shown, on a support 131. The coil 10 may be used to cool a bafile for an oil-diffusion pump, a meissner trap, or other apparatus. Liquid coolant supplied from supply 12 at input 14 is fed to a T connector 16 through tube 17. The coil 10 is cut in the center into a top coil section 18 and a bottom coil section 119 with the two cut ends being connected to the T connector 16 at 20 and 21. Through coils 18 and 19 are shown in vertical alignment, they need not be so located as long as coil section 18 is at a higher elevation so that gravity will cause the gases which form in the coil to rise into this section. A second T connector 23 is provided between the top of coil 10 at 24 and outlet 25 at 26. A high im- 3,529,429 Patented Sept. 22, 1970 pedance coil 27 is connected between the T connector 23 at 28 and the bottom of coil section 19 at 29.

When the coil of the invention is in use, liquid coolant, for example liquid nitrogen continuously converts to gas in the coil 10 and the gas accumulates in the top section 18 of the coil 10 and the liquid remains in the bottom section 19. When the coil is about one-half full with liquid nitrogen, it is refilled. With the liquid nitrogen being supplied at the center of the coil, the initial surge of warm gas from the feed line passes through the gas-filled top section 18 since it presents a much lower impedance than the liquid-filled bottom section 19 which is terminated by a high impedance passage to the exit. The high impedance passage 27 keeps the liquid nitrogen from being ejected from the bottom section 19 of coil 10 during refilling. When the warm gas passes through the top section of the coil and the liquid nitrogen from the pressurized supply tank arrives at the coil, it fills the entire coil. Since the warm gas does not eject the liquid nitrogen from the lower half of the coil, this portion remains cold so that a pressure rise in the vacuum system does not result. This system lends itself very well to automatic time-controlled refilling of the coil and such a system has been operated satisfactorily.

There is thus provided a system for transferring a liquid coolant to a cooling coil that does not have the problems of prior art systems.

While one specific embodiment has been described, it is obvious that numerous changes may be made without departing from the general principles and scope of the invention.

IWhat is claimed is:

1. An apparatus for supplying a liquid coolant from a pressurized liquid coolant supply to a cooling coil for use in a vacuum system; comprising a plural turn tubular cooling coil having its axis in a substantially vertical direction; means for supplying said liquid coolant to the center porton of said coil; output means connected to the top of said cooling coil and a high impedance means connected between the output means at the top of said cooling coil and the bottom of said cooling coil.

'2. The device as recited in claim 1 wherein said cooling coil is cut in the middle to form a top section and a bottom section; said means for supplying liquid coolant to the cooling coil being a T connector .with the cut ends being connected to two arms of the T connector; and the input being connected to the third arm of the T connector.

3. The device as recited in claim 2 wherein said high impedance means is a plural turn tubular coil connected between the top of said cooling coil and the bottom of said cooling coil.

4. The device as recited in claim 3 including a second T connector with the end of the top section of said coil being connected to one arm of said T connector; the top end of said high impedance coil being connected to another arm of said T connector and the output means being connected to the third arm of said T connector.

References Cited UNITED STATES PATENTS 3,279,214 10/1966 Klipping et al. 6255.5 3,396,548 8/1968 Mahe 6255.5

FOREIGN PATENTS 1,049,l,705 11/ 1966 Great Britain.

WILLIAM J. WYE, Primary Examiner U.S. Cl. X.R. 62-5 14 

